This invention relates to needle-suture combinations and particularly to a combination of a surgical needle with a suture in which the force necessary to separate the needle from the suture is within an acceptable range for convenient removal of the needle from the suture by a sharp tug.
In many surgical procedures, surgeons use a technique which employs a non-needled suture and an eyed needle. The needle is threaded by the nurse and the surgeon takes one pass through the tissue using a needleholder. He slips the needle off the suture, returns the needle to the nurse, and is ready for another threaded needle from the nurse. An assistant follows behind and ties the suture.
Some surgeons find that this technique is more simple than using a needled item and cutting the suture with a scissors after each pass. However, the time required for threading results in a significant waste of expensive operating room time.
The security of attachment of eyeless needles to absorbable surgical sutures or to non-absorbable surgical sutures is prescribed in the U.S. Pharmacopoeia, Vol. XVIII at Page 944 (also see U.S. Pharmacopoeia, Vol. XVII, Page 919). It has been the practice of suture manufacturers in the United States and abroad to securely attach the suture to the needle by swaging or with an adhesive so that the minimum pull-out standard recited in the U.S. Pharmacopoeia is met or exceeded.
To avoid the problems discussed above it has been found useful to use needle-suture combinations in which the needle and the suture are readily separable from each other by a sharp tug. Several methods have been devised for preparing needle-suture combinations in which the pull-out values, or the force required for separating the needle from the suture by a straight pull, is within a controlled range.
One approach to the problem is described in co-pending and co-assigned application Ser. No. 409,974, filed Oct. 26, 1973. This approach involves inserting into a drilled hole in the blunt end of the needle one end of a braided suture which has been sized with a resin and is smaller in diameter than the remainder of the suture and then swaging the needle at its blunt end to provide a controlled degree of compression to the end of the suture within the hole. This approach is particularly useful for needle-suture combinations wherein the suture is of large size, i.e., size 4-0 and larger (diameter greater than 7.0 mils), and produces average pull-out values of 3 to 26 ounces, indicating that it takes a straight pull of a magnitude within that range to separate the needle from the suture.
Another approach to the problem is described in co-pending and co-assigned application Ser. No. 446,174, filed by Robert Barclay Duncan on Feb. 27, 1974. In this approach sufficient tension is applied to the suture in a swaged needle-suture combination to move the suture relative to the needle recess and the tension is released when the force drops to the range desired for the pull-out value, the range varying for different sizes of suture. This approach is applicable to a broad range of suture sizes, including sizes as small as 8-0.
The present invention provides another approach to the problem and provides for easy separation of needles from needle-suture combinations without requiring any change in the manner of manufacture of the needlesuture combinations. It also permits the conversion of existing stocks of needle-suture combinations to products from which the needles can be separated by application of moderate force.